The turbo has the ability to do HSPA and hspa+ on att. The turbo only has band 4 and band 13 of lte. Att does use band 4, but I think it's different from what Verizon and T-Mobile use. So, I'd say lte is doubtful.
Find a friend with att with a nano sim and try it on the turbo and see for yourself...
Facebook
Twitter
Instagram